1. Field of the Invention
The present invention relates to an exposure method and device. More particularly, the present invention relates to an exposure method and device for forming an exposure pattern on a printed wiring board, package or semiconductor substrate (semiconductor wafer) with a plurality of optical sources capable of irradiating light on different irradiating areas and at scanning pitches. Further, the present invention relates to a medium into which a program for executing the above exposure method is incorporated.
When a printed circuit board or package is manufactured by a conventional manufacturing method, a pattern such as a wiring pattern is formed by a technique, called photolithography, using a photomask.
2. Description of the Related Art
A conventional exposure method according to the photolithography technique uses a set of photo masks. Exposure light emitted from the optical source passes through the photo mask and is irradiated on the substrate, on the surface of which a resist is coated. Due to the irradiation of light, the exposed portion is formed according to the pattern profile of the photo mask. However, in the conventional exposure method using a set of photo masks, it is necessary to reproduce, maintain and keep the photo mask, which is expensive. Further, when the design is changed, it is necessary to remake the mask, which is also expensive.
A maskless exposure method is also known. In this method, the laser beam is directly irradiated onto the substrate, on the surface of which the resist is coated, by a laser beam source. On the other hand, the substrate or the laser beam source is subjected to scanning according to a predetermined pattern. Drawing data, which are uniformly digitized, are inputted into optical source unit by the high speed memory. Due to the above scanning conducted by the laser beam, the exposed section can be formed.
However, it is necessary to reduce the beam size and the scanning pitch to obtain a fine pattern. Necessarily, the quantity of drawing data to be processed is increased, and it becomes difficult or impossible to quickly process such a large quantity of drawing data by the system of the exposure device. As a result, throughput is lowered.